reworked mesh decimation yes

LightlessSync/ThirdParty/Nanomesh/Algo/NormalsCreator.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace Nanomesh
+{
+    public class NormalsModifier
+    {
+        public struct PosAndAttribute : IEquatable<PosAndAttribute>
+        {
+            public int position;
+            public Attribute attribute;
+
+            public override int GetHashCode()
+            {
+                return position.GetHashCode() ^ (attribute.GetHashCode() << 2);
+            }
+
+            public bool Equals(PosAndAttribute other)
+            {
+                return position == other.position && attribute.Equals(other.attribute);
+            }
+        }
+
+        public void Run(ConnectedMesh mesh, float smoothingAngle)
+        {
+            float cosineThreshold = MathF.Cos(smoothingAngle * MathF.PI / 180f);
+
+            int[] positionToNode = mesh.GetPositionToNode();
+
+            Dictionary<PosAndAttribute, int> attributeToIndex = new Dictionary<PosAndAttribute, int>();
+
+            for (int p = 0; p < positionToNode.Length; p++)
+            {
+                int nodeIndex = positionToNode[p];
+                if (nodeIndex < 0)
+                {
+                    continue;
+                }
+
+                Debug.Assert(!mesh.nodes[nodeIndex].IsRemoved);
+
+                int sibling1 = nodeIndex;
+                do
+                {
+                    Vector3F sum = Vector3F.Zero;
+
+                    Vector3F normal1 = mesh.GetFaceNormal(sibling1);
+
+                    int sibling2 = nodeIndex;
+                    do
+                    {
+                        Vector3F normal2 = mesh.GetFaceNormal(sibling2);
+
+                        float dot = Vector3F.Dot(normal1, normal2);
+
+                        if (dot >= cosineThreshold)
+                        {
+                            // Area and angle weighting (it gives better results)
+                            sum += mesh.GetFaceArea(sibling2) * mesh.GetAngleRadians(sibling2) * normal2;
+                        }
+
+                    } while ((sibling2 = mesh.nodes[sibling2].sibling) != nodeIndex);
+
+                    sum = sum.Normalized;
+
+
+                } while ((sibling1 = mesh.nodes[sibling1].sibling) != nodeIndex);
+            }
+
+            // Assign new attributes
+
+            // TODO : Fix
+        }
+    }
+}